A problem common to nuclear reactors is the safe storage of radioactive reactor components which are unfit for further use. Since available storage space is limited, the volume of the materials to be stored must be minimized. Among the components of a boiling water reactor which must be discarded after a period of use, but which remain radioactive, are the control rod blades and fuel channels of the reactor.
The control rod blades of a boiling water reactor typically have a cruciform cross section in their main blade structure, comprising four blade sections positioned at right angles to each other around a central spline. In one example, the overall length of a control rod blade is approximately twelve feet, while its maximum cross sectional dimension, i.e. twice the width of a blade section, may be on the order of ten inches. A typical control rod blade further comprises an upper handle positioned above the aforesaid main blade structure, upper ball rollers and a lower casting including a velocity limiter.
Each fuel channel of a boiling water reactor typically consists of a hollow, linear, elongate, 4-sided channel of integral construction, which, except for its rounded corner edges, has a substantially square cross section. Each channel may be roughly fourteen feet long by five inches square.
Heretofore, one technique for reducing the volume of a spent control rod blade has been to sever the upper and lower portions from the control rod blade. In the remaining main blade structure the individual blade sections are then removed from the central spline by longitudinal cuts and the separate parts are then stacked and buried together. Since the blades enclose neutron absorber rods which contain radioactive gas, these latter cuts must be made quite near the central spline. The cuts are very difficult and time consuming to carry out because the nozzle of a cutting torch or the blade of a saw can not easily be fitted into the restricted region where the cut must be made.
A commonly practiced technique for reducing the volume of a spent fuel channel has been to crush it into a generally flat configuration. This process often yields random shaped and nonuniform configurations which are difficult to compact in close proximity to each other. Further, the process is prone to create loose segments of the radioactive metal and special care is required to store these pieces together with the crushed fuel channel.